HAL串口库的分析于修改

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tanic 发布时间：2019-1-17 17:00

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本帖最后由 tanic 于 2019-1-17 17:02 编辑

之前做一个项目，串口收发频繁就老卡死，后来用了保守法度过去，近来有空详细分析，发现了问题，并解决，这里分享一下。

这里不对基本操作分析，仅仅讨论一种方式，能让我们稳定的用串口，本文会对HAL库进行些微的修改。
HAL库的串口大致可以分解为2个部分，一个是寄存器控制部分，一个是数据传输部分。我接下来的只修改寄存器控制部分一点点内容，数据传输部分不变，任然采用其回调函数形式，下面具体说明。
一般来说最常用的是发送数据HAL_UART_Transmit，中断接收数据HAL_UART_Transmit_IT。串口其余，如DMA什么的不做分析。
研究一下会发现，HAL库中强制对串口进行了半双工限制，其实STM32的串口是全双工的，很多时候卡死，是因为我们做了全双工操作导致的卡死(不是HAL_UART_STATE_READY状态)。
HAL_UART_Transmit修改后如下

HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout)
{
uint16_t* tmp;
uint32_t tickstart = 0U;
/* Check that a Tx process is not already ongoing */
// if(huart->gState == HAL_UART_STATE_READY)
{
if((pData == NULL ) || (Size == 0U))
{
return HAL_ERROR;
}
/* Process Locked */
// __HAL_LOCK(huart);
huart->ErrorCode = HAL_UART_ERROR_NONE;
huart->gState = HAL_UART_STATE_BUSY_TX;
/* Init tickstart for timeout managment*/
tickstart = HAL_GetTick();
huart->TxXferSize = Size;
huart->TxXferCount = Size;
while(huart->TxXferCount > 0U)
{
huart->TxXferCount--;
if(UART_WaitOnFlagUntilTimeout(huart, UART_FLAG_TXE, RESET, tickstart, Timeout) != HAL_OK)
{
return HAL_TIMEOUT;
}
if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE))
{
tmp = (uint16_t*) pData;
huart->Instance->TDR = (*tmp & (uint16_t)0x01FFU);
pData += 2;
}
else
{
huart->Instance->TDR = (*pData++ & (uint8_t)0xFFU);
}
}
if(UART_WaitOnFlagUntilTimeout(huart, UART_FLAG_TC, RESET, tickstart, Timeout) != HAL_OK)
{
return HAL_TIMEOUT;
}
/* At end of Tx process, restore huart->gState to Ready */
huart->gState = HAL_UART_STATE_READY;
/* Process Unlocked */
// __HAL_UNLOCK(huart);
return HAL_OK;
}
// else
// {
// return HAL_BUSY;
// }
}

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HAL_UART_Transmit_IT修改如下，除了祛除限制，还屏蔽了中断使能，这个后面再说原因

HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
/* Check that a Rx process is not already ongoing */
// if(huart->RxState == HAL_UART_STATE_READY)
{
if((pData == NULL ) || (Size == 0U))
{
return HAL_ERROR;
}
/* Process Locked */
// __HAL_LOCK(huart);
huart->pRxBuffPtr = pData;
huart->RxXferSize = Size;
huart->RxXferCount = Size;
/* Computation of UART mask to apply to RDR register */
UART_MASK_COMPUTATION(huart);
huart->ErrorCode = HAL_UART_ERROR_NONE;
huart->RxState = HAL_UART_STATE_BUSY_RX;
/* Process Unlocked */
// __HAL_UNLOCK(huart);
/* Enable the UART Error Interrupt: (Frame error, noise error, overrun error) */
// SET_BIT(huart->Instance->CR3, USART_CR3_EIE);
/* Enable the UART Parity Error and Data Register not empty Interrupts */
// SET_BIT(huart->Instance->CR1, USART_CR1_PEIE | USART_CR1_RXNEIE);
return HAL_OK;
}
// else
// {
// return HAL_BUSY;
// }
}

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接收中断，屏蔽了清除中断的两行，中断开启后就不再停止了

static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart)
{
uint16_t* tmp;
uint16_t uhMask = huart->Mask;
/* Check that a Rx process is ongoing */
if(huart->RxState == HAL_UART_STATE_BUSY_RX)
{
if ((huart->Init.WordLength == UART_WORDLENGTH_9B) && (huart->Init.Parity == UART_PARITY_NONE))
{
tmp = (uint16_t*) huart->pRxBuffPtr ;
*tmp = (uint16_t)(huart->Instance->RDR & uhMask);
huart->pRxBuffPtr +=2;
}
else
{
*huart->pRxBuffPtr++ = (uint8_t)(huart->Instance->RDR & (uint8_t)uhMask);
}
if(--huart->RxXferCount == 0)
{
/* Disable the UART Parity Error Interrupt and RXNE interrupt*/
// CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));
/* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */
// CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);
/* Rx process is completed, restore huart->RxState to Ready */
huart->RxState = HAL_UART_STATE_READY;
HAL_UART_RxCpltCallback(huart);
return HAL_OK;
}
return HAL_OK;
}
else
{
/* Clear RXNE interrupt flag */
__HAL_UART_SEND_REQ(huart, UART_RXDATA_FLUSH_REQUEST);
return HAL_BUSY;
}
}

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在usart.c添加如下代码，
StartUART_Rx：开启中断，同时开启HAL数据流。本来调用HAL_UART_Receive_IT会重新开启中断，不过前面我把它屏蔽了，这样，这里初始化开一次就行了，上面代码中关中断部分已经屏蔽了
HAL_UART_RxCpltCallback:接收中断回调函数
HAL_UART_ErrorCallback:错误中断回调函数